Let $f(\mathrm{x})= \begin{cases}(1+\mathrm{ax})^{1 / \mathrm{x}} & , \quad \mathrm{x} \lt 0 \\ 1+\mathrm{b}…
be continuous at $x=0$. Then $e^a b c$ is equal to
- $64$
- $72$
- $48$
- $36$
Solution
& f\left(0^{-}\right)=\mathrm{e}^{\lim _{x \rightarrow 0} \frac{\mathrm{ax}}{\mathrm{x}}}=\mathrm{e}^{\mathrm{a}} \\ & \mathrm{f}(0)=1+\mathrm{b} \\ & \mathrm{f}\left(0^{+}\right)=\frac{\frac{1}{2 \sqrt{\mathrm{x}+4}}}{\frac{1}{3}(\mathrm{x}+\mathrm{c})^{-\frac{2}{3}}}=\frac{\frac{1}{2(2)}}{\frac{1}{3} \cdot \mathrm{c}^{-\frac{2}{3}}} \\ & =\frac{3}{4} \mathrm{c}^{2 / 3}
\end{aligned}$
Also at $\mathrm{x}=0$;
$c^{1 / 3}=2 \Rightarrow c=8$
So $\mathrm{f}\left(0^{+}\right)=\frac{3}{4}(8)^{2 / 3}=3$
Now, $\mathrm{e}^{\mathrm{a}}=\mathrm{b}+1=3$
$\mathrm{e}^{\mathrm{a}} . \mathrm{b} \cdot \mathrm{c}=3 \cdot 2 \cdot 8=48$
Asked in: JEE Main 2025 (03 Apr Shift 1)
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